Add tests to ensure that success messages are green and error messages are red

In an attempt to eliminate the possibility of a trivial regression, tests should be included to verify that
- Success messages are output to the console with a green colour; and,
- error messages are output to the console with a red colour!

I haven't included these tests as I'm not _yet_ sure how to go about testing this.

The module I use to colourize the output namely, [Chalk](https://github.com/chalk/chalk), does so by emitting [ANSI escape codes](https://en.wikipedia.org/wiki/ANSI_escape_code) however, the terminal interprets these ANSI escape codes before I can evaluate them. Hm :confused:.